OFFICIAL

CSE Glazing Chapter: Marauding Terrorist Attacks

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Essential Reading

Introduction

Glazing can be particularly vulnerable to manual forced entry, gunshots and explosives.  

However, research conducted by CPNI has demonstrated that glazing has the potential to offer a delay to marauding attackers using bladed weapons or firearms. Please refer to https://extranet.cpni.gov.uk/resources/introduction-marauding-terrorist-attack-standard-mtas
 

Products

MTAS focusses on the delay a barrier can afford against the attacks stated within MTAS.  

CPNI has not been able to evaluate every variant of glazing currently on the market to award each type a MTAS sophistication level. However, following design features were found to offer greater resistance to entry during research trials conducted by CPNI:

  • Double glazed units comprising toughened glass on the attack face and 6.8mm thick PVB laminated glass to the rear are capable of providing at least 30 seconds resistance to BASIC sophistication (bladed weapon) attacks, LOW sophistication ballistic forced entry (BFES) attacks and MODERATE sophistication ballistic forced entry (BFES) attacks.
  • Double glazed units comprising toughened glass on the attack face and laminated glass incorporating a 1.52mm thick PVB interlayer to the rear are capable of providing at least 1 minute resistance to BASIC sophistication (bladed weapon) attacks, LOW sophistication ballistic forced entry (BFES) attacks and MODERATE sophistication ballistic forced entry (BFES) attacks.
  • Double glazed units two layers of laminated glass incorporating a 1.52mm thick PVB interlayer are capable of providing at least 2 minutes resistance to BASIC sophistication (bladed weapon) attacks, LOW sophistication ballistic forced entry (BFES) attacks and MODERATE sophistication ballistic forced entry (BFES) attacks.
  • Laminated glazing units incorporating a 1.52mm thick PVB interlayer are capable of providing at least 1 minute resistance to BASIC sophistication (bladed weapon) attacks, LOW sophistication ballistic forced entry (BFES) attacks and MODERATE sophistication ballistic forced entry (BFES) attacks.
  • Nominally 11.3 mm thick anti-bandit laminated glazing units incorporating a pair of 1.14mm thick PVB interlayers are capable of providing at least 2 minutes resistance to BASIC sophistication (bladed weapon) attacks, LOW sophistication ballistic forced entry (BFES) attacks and MODERATE sophistication ballistic forced entry (BFES) attacks.
  • Laminated glass formed using two layers of 6 mm thick glass sandwiching a 3 mm SentryGlas (SGP) interlayer is capable of providing at least 4 minutes resistance to BASIC sophistication (bladed weapon) attacks, LOW sophistication ballistic forced entry (BFES) attacks and MODERATE sophistication ballistic forced entry (BFES) attacks.

Further CPNI research found that:

  • Annealed glass (also often called float glass), provides very little resistance to forcible attack unless it is either used to form a laminated unit or an anti-shatter film is applied to its rear face.  
  • Although toughened glass (sometimes referred to as tempered glass or safety glass) is slightly stronger than annealed glass, the manner in which it fractures means it offers minimal delay to an attacker using force.
  • Where it is not practical to replace annealed or toughened glass, their resistance to forcible attack can be improved by applying anti-shatter film to the rear face. This helps to hold the fragments in place when the glass breaks, maintaining a barrier. This also reduces the risk to personnel and members of the public from flying glass fragments created if an explosive device is detonated nearby. Extending the film into the glazing retention system is much more effective than when the film is installed only to the vision panel (termed “daylight filming”). Further guidance is available here - https://www.cpni.gov.uk/window-retrofit-options
  • Glazed façades, glazed doors, glazed walls, and door vision panels can allow attackers to see potential targets within the secured area. Frosted glass (also commonly referred to as privacy glass or opaque glass) is preferable because it blocks attackers’ line of sight whilst allowing much of the light to pass through. Frosted films can be retrofitted to existing glass to achieve the same effect.

Further information can be found in CPNI MTA guidance entitled MTA Supplementary Guidance - Physical Barriers that delay and discourage attackers.  

The services of a reputable security consultant with demonstrable experience in the relevant area should be sought if further advice is required.